$ (0.05\% \div -5\%) \div -20\% $
Convert each percentage into a decimal dividing by $100$ $ (0.0005 \div -0.05) \div -0.2 $ $ = 0.0005 \div (-0.05 \times -0.2)$ $ = 0.0005 \div 0.01$ ${0}$ ${1}$ ${0}$ ${5}$ ${0}$ $\text{Shift the decimal 2 to the right.}$ ${5}$ $\text{How many times does }10\text{ go into }{5}\text{?}$ ${0}$ ${0}$ ${5}$ $-\vphantom{0}$ ${5}\div10={0}\text{ or }10\times{0} = {0}$ ${0}$ $\text{How many times does }10\text{ go into }{50}\text{?}$ ${5}$ ${5}$ ${0}$ ${0}$ $-\vphantom{0}$ ${50}\div10={5}\text{ or }10\times{5} = {50}$ $0.0005 \div 0.1 = 0.005$ Convert the decimal into a percentage by multiplying by $100$. $0.005 = 0.5\%$